Palas Fidas 200 E, Operating Manual

Page: 80 / 106

6 Verifying and calibrating measuring system
80 5200-en_V2.0_06/20
6.4 Checking aerosol sensor zero point
To check the zero point, a special filter (HEPA filter) that holds back all parti-
cles from the air is placed on the IADS tube inlet.
If there is only clean air with no particles in the measuring system, the pa-
rameter
Cn
in the screen
data
is 0.
Cn: 0.00
Screen
data
with parameter
Cn
Prerequisites for checking zero point
• Calibration mode is activated.
• The device has been tested for leakage and verified.
Performing test
1. Detach the sampling head.
2. Attach a HEPA filter to the IADS tube inlet.
3. Select
Main menu > data.
4. Observe the value of the parameter
Cn
: The value has to return to zero
within one minute.
5. Remove the HEPA filter.
If the value does not go back to zero:
1. Check that the HEPA filter is seated properly.
2. Clean the optical glasses on the aerosol sensor; refer to section
" Cleaning aerosol sensor optical glasses [
}
93] .”
3. Check that there is no electronic interference that could distort the dis-
play.
4. Inform Palas or your sales partner.